Yes, it can make a huge difference. I did this once when I had arrays of ~1 million floats and had to compute statistics on them. I wound up implementing a bunc

Yes, it can make a huge difference. I did this once when I had arrays of ~1 million floats and had to compute statistics on them. I wound up implementing a bunch of stats functions as C stored procedures that operate on arrays, and brought query times down from ~12 seconds to ~20 milliseconds: https://github.com/pjungwir/aggs_for_arrays/ https://github.com/pjungwir/aggs_for_arrays/ Another time arrays are handy is when you don't know how many "columns" you need to return. SQL can't do this, but a variable-length array can. Here is a writeup for one time that came in handy: http://illuminatedcomputing.com/posts/2013/03/fun-postgres-puzzle/ http://illuminatedcomputing.com/posts/2013/03/fun-postgres-p... Another time they are helpful is to throw an `array_agg` into an aggregate query to see what values are getting rolled up. This can be really useful if you're trying to debug weird behavior. Also `(array_agg(...))[1]` is a poor-man's `first` function. :-)